Engine vibrations without CEL

Hi guys, I have gradually noticed something getting progressively worse on my car, and I have always gotten great help here before! Anyway, it is a 2001 Carrera Cab, with 120 k miles on it. It has worked great, and still does, during the 3 k miles I have driven it. In the beginning it was so smooth, and fast. The AOS was broken when I bought it, and was replaced without any problems. However, it has always had a tendencey to have an unsteady idle, and the rough running test in the Durametric has shown high values. No CEL or any errors shown in Durametric. My concern is that the last month or so, I have noticed a slight hesitation around 4 k rpm, and a vibration from the engine/trans from 3000-4500 rpms or so. There has also emerged something that sounds like valve train noise, like a hydraulic lifter not working properly. It only comes when I rev the engine. Could it be related to the dual mass flywheel? I can feel the clutch vibrating, and I have a feeling I am closing in on a clutch job. So, do you recognize my symptoms? Regards, Johan

Ageing: MAF, Vario-Cam actuaters & chain wear pads, DMF, engine oil, ...

Engine & trans mounts, fuelpump, clogged injecters,sparkplugs,...

Quotes source post: 9841396

My advice would be to with as little (ideally none) engine running as possible get the car to a pro and have him diagnose the cause of the symptoms. The noise you mention could come from many places to name just a few like a loose spark plug, or a leaking exhaust -- last thing touched on purpose or be accident during the AOS repair for example -- but it could be something unrelated to the AOS repair, like a broken valve spring or a bad lifter. The vibration can be from the engine not running as smooth as it should and having a different vibration harmonic which the engine mounts, etc, are not tuned to deal with as well as if the engine were running with its normal smoothness. Certainly the dual mass flywheel can be a cause of the vibration but less likely (highly unlikely) to be the source of the engine noise. Dual mass flywheels have been known to break (the dual mass feature that is) and cause not only odd clutch engagement/take up but other symptoms. Regardless if any of the things above are or are not what's going on none of them will fix themselves. Someone somewhere has got to get his hands dirty. And the more you engage in self-diagnosis the more risk you assume from if the symptom is the tip of an iceberg serious problem doing more damage. The engine may be sick but not deathly sick. (My 02 Boxster experienced a failed VarioCam solenoid/actuator and was clearly sick, sick, sick, but was healed/cured by having the bad parts replaced.) Get the car to a pro. Describe to him as best you can what happens and when and let him earn his pay by diagnosing what's going on. Sincerely, Macster.

Thanks, great advice. I just wish we had a good Porsche mechanic in my city, but we dont, unfortunately. So I am afraid I have to diagnose it myself. The solenoid should produce a CEL, shouldnt it? I cant say that I have experienced any lack of power, besides the slight hesitation I sense when the vibrations start. And the vibrations seems to vanish with higher revs, or at least I cant feel them. The DMF seems to work, the clutch engagement is normal but I can feel a vibration when pressing or releasing the pedal. It feels like a slightly worn clutch. I guess it could be a broken valve spring or a bad lifter. How do I diagnose that? Could it be IMS related? Could be a bearing rattle. Thanks, Johan Regards, Johan

I read some threads, and it seems like I should start with the throttle body cleaning. Then MAF, then check plugs for fouling, then try to figure out which bank has the rattle. Pic of the car: Thanks, Johan

Quotes source post: 9842431

Before you do anything else, unscrew the oil filter housing and dump the oil into a *clean* (spotless!) drain pan and carefully examine the oil and the filter element for any scary bits. What you see or do not see is important. If you see scary bits -- post pics! -- you're done. The car (with *no* engine running) has to be taken to a qualified shop for professional attention. If you see nothing in the oil, then you can clean the TB but if it is dirty there's another problem. The only time I have bothered to clean the TB of any of my cars is when I removed the TB of my 02 Boxster in an attempt to diagnose what proved to be a bad AOS. The TB was dirty, oily, with a puddle of oil behind the TB at where the hose from the AOS connected to the intake manifold. The TB clean helped for a few minutes then the failing AOS oiled the thing up again and that coupled with the other things a faIling AOS does the engine just got sicker. But before you bother with the TB cleaning, that noise I think is more important. It is out of the ordinary and out of the ordinary noises always come before dirty TBs. You need to as best you can with as little engine running as possible ID the source of the noise. Where the noise comes from really determines what you do next. BTW nice color! My 02 Boxster is that color and I still think its beautiful. Sincerely, Macster.

Hi again, I finally had an hour to look through the great advice from Macster above. Just to prepare you; this is not easy things to present on a picture, but please see me trying below.... :-) First and foremost; I replaced the oil filter cartridge and saved the half quart of oil that came with it. Then I cut out about a fifth of the filter material, and took a few pics with flash and without. Last one is the flash picture. The black particles you see on the pic doesn't seem to be ferrous. I continued by first sweeping my magnet in the half quart of oil, thouroghly. The magnet looked like this afterwards: Then I swiped the filter element, and that added this much on the magnet: Don't know if you see the difference, but the amount of stuff on the magnet maybe doubled. Any thoughts? Should I scrape the filter to gather all the particles? The oil has maybe 2000 miles on it. So, I continued to remove the air filter housing to access the TB. The TB had some residue, not much, so I swiped it clean. After cleaning it looked like this: Only thing is that it doesn't close all the way? There is a few millimeters gap there. I looked around the engine, and it looked nice and dry: Couldn't see any missing cables or hoses. I followed the vacuum lines, and they were correctly connected. But, I found this black rubber hose stuck behind the air pump (?) in the left back corner of the engine bay: It is straight but I bent it to get all of it on one fick. It is about a foot long, less than 5 millimeter ID. The MAF looked super clean, but I guess that one is impossible to see if it works or not: Any thoughts on how to check the MAF? Regarding the vibrations; when I drove it into the carport, I tried to feel how it ran. It is clear that the vibrations are there from start, meaning from idle and all the way up. Once you guys clear the oil residue or not I will start it up and try to catch the rattle on a youtube clip. Please let me know your thoughts! Regards, Johan

My thought - Truthfully if I had an oil filter that looked like that I would be making a call to the credit union for a second mortgage in order to fund a rebuild or replacement engine! I would not start that engine again until at least you pull and check the IMS/bearing...might as well replace it at that point. I would get that car to someone who is knowledgeable about what you are facing and can give you some professional advice. Hate to say it, but it really looks like you have some internal engine problem and if you continue to run it you run the risk of complete failure vs. repair. Just for contrast...I have a 99 C2 with 120,000+ miles, no vibrations throughout the entire RPM range, no funny sounds or ticking noises, runs and sounds as sweet as a sewing machine. I never have any particles whatsoever in the filter/oil. I am not an IMS freak by any means, but you've got something going on and you need to get in there and find out what.

Wow, is it that bad? I didnt think that I had a problem with just these few tiny particles present. I have seen other filter elements with big shiny chuncks of bearing material in, and mine looks nothing like that. Maybe I should remove the oil pan? Maybe there is where the most of the stuff end up. Regards, Johan

Well I was just going to say that filter didn't look too bad. The black non-ferrous bits are usually things like chain guides and it's kind of normal. Ferrous stuff is never good of course. Every 996/7 I've ever been in idles a bit lumpy compared to a smoother layout like an inline 6 you might find in a BMW. Generally the IMS bearings don't give much of a warning sound-wise. If the IMS bearing was going I think you would see a lot of larger particles in the filter. Gotta say you might not be able to "Rennlist WebMD" this one. If it is really bothering you just take it in to somewhere that has an actual Porsche scanner; more than likely the stealership. Also how did you mount those 997 wheels on your 996?

Hi Johan, Your filter looks good to me. Remove the oil fillercap when engine is running, if there is no change in the idle there is intake leak some where. Maybe AOS (again) or in the oil fillertube. Both are known issues wirh these cars. Allso check the sparkplugs and airfilter.

Hi, there are several different 997 "S" wheels, and there is only one specific offset that works. I believe it is the 2S wheels, the 4S has the wrong ET. I can verify if you want to know? I had to mount 10 mm spacers in front, though. I think the wheels look great on the 996! The car also has a GT3 kit and H&R springs. Regarding the oil; I thought so too, meaning it wasn't anything extraordinary. The ferrous particles are really small and very few, and I would have guessed that any engine has them in the oil filter. But I can be wrong, that is why I really appreciate any thoughts from you guys. The lumpy idle would be ok, if my Durametric didn't say the "rough running" value was too high. I guess that indicate a problem. Plus the rattle, which sounds like a non-functioning hydraulic valve lifter. Ideas on next step? Should I start it and try and get a clip with the rattle? Or take down the oil pan? Regards, Johan

Quotes source post: 9868149

Definetly need to drop the oil sump plate & see whats in there & clean the oil pickup. The metal in your filter was after only 2000 miles so I would be concerned.

+1 on Byprodriver. That is what I was getting at...that much "stuff" in the filter after 2000 miles? You are asking fellow posters and members a dangerous question...should I run it or not? My opinion was not to run it and find out exactly what is wrong, or run the risk. I guarantee this - if it is something like a stuck lifter, rod bearing, IMS bearing or some other internal component going bad - run it and you will soon find out exactly what it is. I would sigh heavily and realize that it is time to bring in a professional or go in yourself.

Sounds like bad engine mounts. Nick

Quotes source post: 9868149

Ferrous metal bits in an older engine that has not been opened up is troubling enough but coupled with change in idle smoothness.... I do not wish to be an alarmist but you could be tempting fate with your on-going attempts to self-diagnose this. IOWs, everytime you start the engine run the engine at all you are tempting the engine gods. I do not think dropping the oil sump pan is worth the effort. The pump oil pickup is very close to the bottom of the sump and if a piece is small enough to make it through the rather coarse screen it gets inhaled and run through the pump and comes out in tiny bits and ends up in the oil filter or oil filter housing oil. If there are bigger pieces that can't fit through the screen I think you'd know it from how sick the engine was running. These engines do not have a lot of superfluous ferrous metal to shed. Every piece of ferrous metal is significant in that it is present at all. If you want a next step -- though as I started out with above any engine run time at this stage is very very risky and ill-advised -- would be to diagnosis the source of that noise. (It now occurs to me that maybe you removing the oil sump is better than possibly pointing you to doing anything that involves starting/running the engine...that removing the oil sump vs. running the engine is the lesser of two evils.) But you are a big boy I believe able to make the best decision for you. But take your time. You are playing for rather high stakes in this endeavor. Ok, so if you are willing to accept the risk any engine running brings with it if you can id the noise coming from up under one or the other camshaft cover that suggests the noise is a bad lifter or a broken valve spring. The latter especially can account for the ferrous metal bits in the oil. They are the remnants of a fragment of the valve spring. Less likely a bad lifter sheds any metal. They just get noisy they do not (very rarely anyhow) they do not come apart. If you determine the noise is *not* coming from under the camshaft covers but from deeper inside the engine you're done. Shut off the engine pronto. Winch the car onto a flat bed and get it to a qualified shop ASAP. In fact even if you find the noise is coming from under a camshaft cover that is not a repair job someone wants to undertake and it is a not a repair job I would entrust to any place other than a Porsche dealer service department or barring one being available then entrusting it to a highly recommended indy who specializes in Porsches. Really then the best advice would be to get the car to a qualfied shop and let any attempt to id the source of noise take place there. In this case you want to make every second the engine runs count. Otherwise, the diagnosis has to be done by I would guess removing the engine and tearing it down and inspecting/examining suspected components for signs of distress this process keeps going until the tech is sure he knows the full extent of the engine's condition. Then the appropriate repairs can be decided upon. Sincerely, Macster.

Hi, I did some reading up on the engine mounts, and that could actually be the source for my vibrations. I have to look into that when I am home after my current business trip. They are really cheap and probably worth changing anyway. There might be more than one reason for my issues. It might be a combination of an air leak, engine mounts and an unknown rattle source. I'm still not entirely sure about the oil. To me the amount of debris seems pretty normal; I guess if I say that it always had this much material in the filter, and I multiply the debris found over 2000 miles compared with 120 k total miles, the total amount of material in the filter over the car's lifetime would be similar to or less than a pea. Not that I am disregarding the great advice above, I will definately look further before I use the car again, but I have to say that it seems pretty normal to me. So I think I will do 3 things this weekend; remove the oil pan, check the engine mounts, and try to isolate the rattle. I might have been unclear about a few things; the idle have always been slightly lumpy, and have not progressed. The rattle I don't know, but it have not gotten worse since I discovered it maybe 1000 miles ago. The vibrations have gotten worse, though. My ongoing problem is that there is no shop where I live, or anywhere within a 100 miles, that I consider to be "qualified". The stealership an hour away charges at least $300 + tax per hour here in Sweden, and their only advantage is that they have a more advanced diagnostics setup than my Durametric. To have them remove the valve covers and check springs would easily cost $2500. So I am pretty sure this will be my last 996, I need to buy a car I can get local help for. Most likely an Audi RS5 or BMW M3. But first I need to get this one running as it should, and preferably enjoy it over the winter. Your advice is very appreciated, please keep any thoughts or ideas coming. Regards, Johan

Hi guys, I woke literally up in the middle of the night, remembering a strange oil puddle under the rear bumper a few months ago. I thought it was strange since the oil didnt look like motor oil, more like very blueblack oil mixed with water. Unfortunately I only thought it was some leftover from the AOS failure, and disregarded it. Now it seems like it was the motor mounts breaking. Arent they using oil in them? I dont know how to diagnose this, I tried to jack the engine up but the body started moving pretty much at the same time. The engine cross bar seems to hang just an inch below the mount, which looks pretty normal to me. Stupidly enough I have looked at the tail pipes for several weeks now, wondering why someone didnt put them closer to the bumper cutouts.... So I ordered new ones. With some luck the rattle might be related to this as well, meaning the vibrations have caused some wear in the exhaust, or simliar. Future will tell! Regards, Johan

Well, it turned out to be the engine mounts. I bought two new ones, $200 shipped, and replaced them yesterday. Now the vibrations are gone, the rattle are gone and I cant feel any issues with the idle either! One of the mounts was cracked without any oil left in it, completely shot to pieces. The other one bursted while I was replacing the first one, but it must have been compromized before. The reason I think so is that both tail pipes raised about 3/4" afterwards.... I hammered down on the exhaust while it was jacked up, and found the left tail pipe to rattle somewhat. I would guess that the excessive vibrations from the non-functioning motor mounts somehow made a weld inside the tip give. And since the vibrations got worse and worse, so did the rattle. Now, without vibrations, no rattle! The idle is still a little mystery. I will post a clip to youtube when I can get the login to work, but I cant feel anything wrong with it. Might have been the vibrations, once more. But, my Durametric still showed high "rough running" values, and that cant be from bad motor mount vibrations.... Thanks all, especially the two of you that made me think about the motor mounts. This is a great forum, I wouldnt have started looking after engine mount failure symptoms without this thread! Regards, Johan

Quotes source post: 9870456

The WINNER!+1

Noises that could be coming from inside the engine; rough running engine; coupled with other things often arise from a sick engine. Glad it proved to be the mounts and not something more serious. I'm still a bit troubled by the ferrous debris in the oil but if you are ok with it then so am I. Sincerely, Macster.

Hi again, so, finally gave up on Youtube and used ol' reliable Photobucket to post my video: And a picture on my fingertip with the ferrous material from the magnet. It is easier to see on a light background. Please let me know your thoughts. The car runs "silky smooth", like the sewing machine it was when I first got it. I can't believe I didnt use it for 6 weeks just because I had bad engine mounts.... :-( Regards, Johan

Those bits on your finger do look smaller. I would change the oil & filter & check the filter again in 1,000 miles.

Well, absent any other signs of engine trouble -- I guess the new mounts cured the vibration and the hesitation and the "valve train noise" -- and with no other bits of seals or bearings or bearing cages or chain tensioner/guide composite plastic present the small amount and small size of the ferrous bits don't look that bad... It is not impossible for a bit of ferrous metal to come loose and after going through the oil pump ending up as some tiny bits of metal in the oil filter housing oil/filter element. I note too you had the AOS done a while back and any time an engine is disturbed this can increase the amount of trash/debris that is found in the oil filter housing oil and the oil filter element. Still I'm bothered by it. Up to you, of course, but you might consider getting some of that filter housing oil analyzed to know what you can't see by your eyes is in the oil. Do not send in what's on your finger you'll get some way out (and scary ppm) readings. Ideally the oil sent in wants to be a sample of oil that is representative of oil's contents, with such a sample not selected from a particularly dirty place like the oil filter housing (which tends to get loaded with stuff that is prevented from going through the filter but is not trapped/held by the filter element fibers) nor from oil that has risen to the top after being drained and allowed to stand around. (Some of the big rig oil change shops use the first technique... there's 10 or more gallons of very expensive engine oil, a large oil filter, and labor cost in the balance...) One technique is as the oil is draining about midway through the drain -- though it can be messy to obtain this sample -- you want to capture a cup or two of this oil in a *clean* container and get this oil into a suitable container to have analyzed. If you have an appropriate oil analysis container handy you can capture the oil directly in this and seal it. Or you could do an oil/filter change and be sure to clean the oil filter housing thoroughly. Then after some engine run time remove the oil filter housing and dump its contents out and see what you can see. Now the question becomes how long do you run the engine. Well, as another poster suggested 1000 miles and that's a good number, provided and this is important, provided you be very on your toes and at the first sign of engine trouble shut the engine off and do not try to limp it home, restart it, etc, but get the car to a shop for trouble shooting. Sincerely, Macster.